Process of preparing raw linen for bleaching operations



GR 1&5015553 jlN 0F TEXTlLES & FIBERS,

Patented July 15, 1924.

UNITED STATES RAFTsa PATENT OFFICE.

CARL BOGHTER, OIE GUNZIBURG, GERMANY.

PROCESS OF PREPARING RAW LINEN FOR IBLEACI-IING OPERATIONS.

No Drawing. Application filed May 12,

To all whom it may concern Be it known that I, CARL BooHTER, citizen of the German Republic, residing at Gunzburg, Bavaria, Germany, have invented certain new and useful Improvements in Processes of Preparing Raw Linen for Bleaching Operations, of which the following is a specification.

The present invention refers to improvements in bleaching raw flax or raw linen fibre. The bleaching of raw linen fibre in order to obtain fibres of white color -'is more diflicult than the bleaching of other vegetable fibres, as for instance cotton. The coloring matters of flax, which may be designed as pectins orpectin compounds are very resistant against the action of bleaching agents, from which reason the known bleaching processes are very tedious and require repeating. If one would use bleaching solutions of high concentration for shortening the duration of the bleaching action, the fibre will be weakened or be destroyed.

The present process consists in treating raw flax or raw linen fibre, as in woven or spun state immediately (i. e., in raw state, Without a previous treatment, as for in stance with caustic or other alkalis) with solutions of bisulphites, whereupon the fibre is treated with acids, the acid is removed by washing with water and subjecting the goods to the action of bleaching agents. It is preferable to repeat the treatment with bisulphites (acids, water) before the final bleaching operation.

Suitable bisulphites .for carrying out the present process are the bisulphites of alkali metals or alkali-earth metals. Suitable acids for carrying out the present process are for instance sulphuric acid or hydrochloric acid.

Suitably the bisulphite solution for the second treatment (if used) has higher concentration than for the first treatment. Preferably one uses for the first treatment a bisulphite solution already used for the second treatment and uses for the latter step fresh bisulphite solutions.

It is generally suitable to use bisulphite solutions of not too high concentration.

Suitable bleachin agents are for instance hypochlorites of so ium or calcium, hydrogen peroxide, peroxides of the alkali metals or earth alkali metals, persalts, as persulphates, perborates, percarbonait'es, preferably of the alkali metals or earth alkali 1922. Serial No. 560,463.

metals. One may combine the action of several bleaching agents, as for instance use mixtures of them, or use one bleaching agent for one treatment and afterwards another for a second treatment. One may use more dilute solutions of the bleaching agents than hitherto. Suitably one treats after the action of the bleaching agents with acids, washes out with water, repeats the use of the bleaching agents, treats with acids, washes out with water, and subjects the fibre to a third action of the bleaching agents, acids and water.

The whole process may be carried out at temperatures below 100 degrees centigrade, preferably at 70 to 80 degrees centigrade.

The process may be carried out at atmospheric pressure, but also at increased or lessened pressure.

Examples.

1. Coarse linen goods (as for instance piece goods), if desired after the singeing operation, are brought into a bisulphite solution, preferably which had already used for the present process and allowed to rest in the solution for about 6 to 8 hours at a temperature of about 50 degrees centigrade. The goods are then taken out of the solu tion, squeezed and then subjected to the action of acids, for instance "a solution of sulphuric acid or hyfigchloricacid of per cent for about ho ur. Tlie acid is washed out with water. Now one brings the goods into a bisulphite solution, preferably already used for the process, suitable of 1 to 3 per cent bisulphite and allows to restthere during about 8 hours at about 70 degrees centigrade. One squeezes, treats with acids, washes with water and treats now with a bleaching agent, whereupon one may treat again with bisulphite solution, preferably fresh. Hy pp c h lgr i t e spl utions used as bleaching ag' nts contain suitably between 0.2 and 0.9 gram active chlorine per liter, the first bleaching bath preferably about 0.9 gram, the second about 0.2 to 0.1 gram. Hydrogen peroxide baths may contain per liter 10 cubic meters H O (of 30 per cent) (if desired added with ammonia for neutralizing acids if present). As the whole hydrogen peroxide is not consumed one may use the baths for repeated times after having added fresh portions of hydrogen peroxide sufiicient for bringing the bath to the suitable percentage. In using perborates (or generally persalts) one uses preferably amounts of the persalts giving the above quoted quantity of hydrogen peroxide.

2. For finer goods it is sufficient to treat once with already-used solution of bisulphite, and to treat after having subjected the goods to the action of acids and to the Washing operation for a second time with fresh solutions of bisulphites whereupon after the treatment with acids and after the washing out of the acids a bleaching operation is carried out, preferably as described before.

It is preferable to move the bisulphite solutions and to lead them through the goods from above to below or inversely. The process may be carried out for piece goods continuously, in leading the bisulphite solutions to the pieces, allowing the solutions to rest and afterwards conducting them to new portions of goods. It is unnecessary to spread out the pieces as required for lawn bleaching.

Finally one may use a soaping operation.

I claim 1. The process for preparing raw linen for the bleaching operations which consists in immersing raw linen in aqueous solutions of bisulph i tes of alkali metals, separating the linen from the liquid, treating the linen with acids capable of decomposing the bisulphites absorbed by the linen and washing out the acids retained by the linen with water whereupon the bleaching operation is carried out.

2. The process for preparing raw linen for the bleaching operations which consists in immersing raw linen in aqueous solutions of bisulphites of alkali metals, separating the linen from the liquid, treating the linen with mineral acids and washing out the acids retained by the linen with water whereupon the bleaching operation is carried out.

3. The process for preparing raw linen for the bleaching operations which consists in immersing raw linen in aqueous solutions of bisulphites of alkali metals, separating the linen from the liquid, treating the linen with sulphuric acid and washing out the sulphuric acid retained by the linen With Water, whereupon the bleaching operation is carried out.

In testimony whereof I hereunto aflix my signature.

CARL BOOHTER.

Witness:

ALESANDER A. on SoTo. 

